Baculoviruses comprise an immense family of DNA-containing viruses which are found in diverse species of arthropods ranging from shrimp to mosquitoes. They are considered to be ubiquitous ina the environment and are naturally present in the human food supply. In addition to their importance in modulating arthropod populations in natural ecosystems, baculoviruses have two major applications; 1) use in the biological control of insert pests and 2) use as gene expression vectors to produce eukaryotic proteins of biomedical interest. The long range objective of this research project is to provide a molecular understanding of host range restrictions to baculovirus infection. Intermediate steps in reaching this goal are to define the molecular strategies by which baculoviruses subjugate cellular processes to achieve their full replicative potential. Of specific interest in this project is defining those baculoviral genes which exhibit host cell-specific effects on viral DNA replication and gene expression. Additional genes affecting baculovirus late and very late gene expression will be identified and athe function of previously identified genes will be further defined. The latter genes include the late expression factor genes (lefs) of Autographa californica nuclear polythedrosis virus (AcMNPV); of particular interest are the genes encoding the putative RNA polymerase subunit, lef-8, and host cell-specific factors hcf-1, ie-2, and lef-7. The molecular mechanisms by which the products of AcMNPV genes influence very late expression will also be examined; these genes include the integrase homolog vlf-1 and the protein tyrosine phosphatase homolog ptp.